Return to BSD News archive
Newsgroups: comp.os.386bsd.questions Path: sserve!manuel.anu.edu.au!munnari.oz.au!spool.mu.edu!howland.reston.ans.net!zaphod.mps.ohio-state.edu!cs.utexas.edu!uunet!super!becker From: becker@super.org (Donald J. Becker) Subject: Re: How to select 72MHz on ET4000 board? Message-ID: <1993Mar4.171002.5808@super.org> Sender: news@super.org (USENET News System) Nntp-Posting-Host: metropolis Organization: IDA Supercomputing Research Center References: <rcpt.730581552@rwb.urc.tue.nl> <1993Feb25.151244.15114@gmd.de> <rcpt.730720661@rwa.urc.tue.nl> Date: Thu, 4 Mar 1993 17:10:02 GMT Lines: 41 In article <rcpt.730720661@rwa.urc.tue.nl> rcpt@urc.tue.nl writes: >veit@borneo.gmd.de (Holger Veit) writes: >>In article <rcpt.730581552@rwb.urc.tue.nl>, rcpt@rwb.urc.tue.nl (Piet Tutelaers) writes: >>|> >>|> The ET4000 board in our 486DX33 box does provide a 72MHz clock in >>|> order to achieve a 70 Hz refresh rate for 1024x768 mode. The manual >>|> explains how to select this frequency with VMODE.EXE an MSDOS utility >>|> (mode 0x38). >>|> >>|> If I startup `startx' and write its output into a file I don't see this >>|> 72MHz clock. Does this mean I can't select this clock with XFree1.2? > >>The clock might be select with a mechanism that is not in the area >>of the standard 16 clocks. This is not supported by XFree86. Another >>possibility is that your VMODE (or the handbook) lies about the 72MHz; >>also already seen. There is a facility to run an external clock >>program (if you manage to find out how the 72MHz clock is enabled), >>see the XFree86-1.2 doc on this. Xfree86 doesn't usually detect the correct clocks in my ET4000. It has some clocks that are far abover the 65Mhz-nominal-max rating of the ET4000, but it Xfree often screws up the lower-rate clocks as well. You can either o run Xfree a bunch of times on an idle machine, and guess at which values are correct, or o Add a 'Clocks' line that just numbers the clocks 0 to 15, and add 'modes' and resolution lines that use every clock. Step through the clock rates to find one that you like. Clocks 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Modes "1024x768-0" "1024x768-1" "1024x768-2" "1024x768-3" "1024x768-4"... If you are curious about the true dot-clock rates, measure the horizontal sync with a frequncy counter and multiply away... DB -- Donald Becker becker@super.org Supercomputing Research Center 17100 Science Drive, Bowie MD 21114 301-805-7482